Interstellar methyl alcohol

Gottlieb, C. A.; Ball, John A.; Gottieb, E.W.; Dickinson, D. F.

doi:10.1086/156747

Cited by 45 publications

(39 citation statements)

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“…Our LTE model shows that, for a temperature of 160 K, the latter two transitions are expected to be as strong as the former two. We conclude from this that either the assignment of the 90 704 MHz line to CH 3 OD in the Kitt Peak spectrum was not correct, or the line reported by Gottlieb et al (1979) traces low-excitation emission of CH 3 OD. Given that the line detected in emission in the Kitt Peak spectrum dominates over the absorption features, opposite to what is seen in the ALMA spectrum, this emission line, if real, must come from a region more extended than the Sgr B2 continuum emission that is absorbed by the diffuse clouds along the line of sight.…”

Section: Deuterated Methanolmentioning

confidence: 74%

“…Comito et al (2003) (Jacq et al 1999). Deuterium fractionation thus does not appear to be generally more efficient on larger scales in Sgr B2, which again questions the detection of CH 3 OD reported by Gottlieb et al (1979).…”

Section: Deuterated Methanolmentioning

confidence: 79%

“…5.4. This discrepancy seriously questions the detection of CH 3 OD reported by Gottlieb et al (1979) toward Sgr B2, unless deuteration of methanol is more efficient by one order of magnitude on large scales in the Sgr B2 cloud compared to the embedded hot cores. Comito et al (2003) (Jacq et al 1999).…”

Section: Deuterated Methanolmentioning

confidence: 90%

“…A detection of CH 3 OD toward Sgr B2 was reported by Gottlieb et al (1979) with the 36 foot radio telescope of the National Radio Astronomy Observatory at Kitt Peak (HPBW ∼ 74 ). These authors detected a line at the frequency expected for the pair of partially blended transitions 2 −1 -1 −1 E (90 703.6 MHz, E u /k B = 11.3 K) and 2 0 -1 0 A (90 705.8 MHz, E u /k B = 6.5 K), but they did not detect the nearby 2 1 -1 1 E transition (90 743.5 MHz, E u /k B = 15.6 K), which is in fact expected to be partially blended with the 10 1 -9 2 A transition (90 741.7 MHz, E u /k B = 124 K).…”

Section: Deuterated Methanolmentioning

confidence: 96%

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Exploring molecular complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)

Беллоче

Müller

Garrod

et al. 2016

A&A

200

345

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Context. Deuteration is a powerful tracer of the history of the cold prestellar phase in star-forming regions. Apart from methanol, little is known about deuterium fractionation of complex organic molecules in the interstellar medium, especially in regions forming high-mass stars. Aims. Our goal is to detect deuterated complex organic molecules toward the high mass star-forming region Sagittarius B2 (Sgr B2) and derive the level of deuteration for these molecules. Methods. We use a complete 3-mm spectral line survey performed with the Atacama Large Millimeter/submillimeter Array (ALMA) to search for deuterated complex organic molecules toward the hot molecular core Sgr B2(N2). We constructed population diagrams and integrated intensity maps to fit rotational temperatures and emission sizes for each molecule. Column densities are derived by modeling the full spectrum under the assumption of local thermodynamic equilibrium. We compare the results to predictions of two astrochemical models that treat the deuteration process. Results. We report the detection of CH 2 DCN toward Sgr B2(N2) with a deuteration level of 0.4%, and tentative detections of CH 2 DOH, CH 2 DCH 2 CN, the chiral molecule CH 3 CHDCN, and DC 3 N with levels in the range 0.05%-0.12%. A stringent deuteration upper limit is obtained for CH 3 OD (<0.07%). Upper limits in the range 0.5-1.8% are derived for the three deuterated isotopologues of vinyl cyanide, the four deuterated species of ethanol, and CH 2 DOCHO. Ethyl cyanide is less deuterated than methyl cyanide by at least a factor five. The [CH 2 DOH]/[CH 3 OD] abundance ratio is higher than 1.8. It may still be consistent with the value obtained in Orion KL. Except for methyl cyanide, the measured deuteration levels lie at least a factor four below the predictions of current astrochemical models. The deuteration levels in Sgr B2(N2) are also lower than in Orion KL by a factor of a few up to a factor ten. Conclusions. The discrepancy between the deuteration levels of Sgr B2(N2) and the predictions of chemical models, and the difference between Sgr B2(N2) and Orion KL may both be due to the higher kinetic temperatures that characterize the Galactic center region compared to nearby clouds. Alternatively, they may result from a lower overall abundance of deuterium itself in the Galactic center region by up to a factor ten.

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Section: Deuterated Methanolmentioning

confidence: 74%

Section: Deuterated Methanolmentioning

confidence: 79%

Section: Deuterated Methanolmentioning

confidence: 90%

Section: Deuterated Methanolmentioning

confidence: 96%

See 2 more Smart Citations

Exploring molecular complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)

Беллоче

Müller

Garrod

et al. 2016

A&A

200

345

View full text Add to dashboard Cite

show abstract

“…CH 3 OH, on the other hand, has usually quite low abundance and is difficult to detect outside hot, dense cloud cores. Nevertheless, Gottlieb et al (1979) found the 834 MHz (1 1 − 1 1 )A ∓ line in the CMZ in emission and extended relative to their 40 beam, concluding it is (weakly) inverted and amplifying the strong background radio emission.…”

Section: Shock Chemistry In G16−0025mentioning

confidence: 92%

Molecules in G1.6–0.025—“HOT” Chemistry in the Absence of Star Formation at the Periphery of the Galactic Center Region

Menten

Wilson

Leurini

et al. 2009

ApJ

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We present molecular line mapping of the Giant Molecular Cloud G1.6−0.025, which is located at the highlongitude end of the Central Molecular Zone (CMZ) of our Galaxy. We assess the degree of star formation activity in that region using several tracers, and find very little. We made a large-scale, medium (2 ) resolution map in the J = 2 − 1 transition of SiO for which we find clumpy emission over a ∼ 0.• 8 × 0.• 3 sized region stretching along the Galactic plane. Toward selected positions we also took spectra in the easy-to-excite J k = 2 k − 1 k quartet of CH 3 OH and the carbon monosulfide (CS) 2 − 1 line. Throughout the cloud these CH 3 OH lines are, remarkably, several times stronger than both the CS and the SiO lines. The large widths of all the observed lines, similar to values generally found in the Galactic center, indicate a high degree of turbulence. Several high LSR velocity clumps that have 50-80 km s −1 higher velocities than the bulk of the molecular cloud appear at the same projected position as "normal" velocity material; this may indicate cloud-cloud collisions. Statistical equilibrium modeling of the CH 3 OH lines observed by us and others yields relatively high densities and moderate temperatures for a representative dual velocity position. We find 8×10 4 cm −3 /30 K for material in the G1.6−0.025 cloud and a higher temperature (190 K), but a 50% lower density in a high-velocity clump projected on the same location. Several scenarios are discussed in which shock chemistry might enhance the CH 3 OH and SiO abundances in G1.6−0.025 and elsewhere in the CMZ.

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Global Fit of Torsion–Rotational Transitions in the First Three Torsional States of CH3OD

Duan

McCoy

2000

Journal of Molecular Spectroscopy

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Interstellar methyl alcohol

Cited by 45 publications

References 0 publications

Exploring molecular complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)

Exploring molecular complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)

Molecules in G1.6–0.025—“HOT” Chemistry in the Absence of Star Formation at the Periphery of the Galactic Center Region

Global Fit of Torsion–Rotational Transitions in the First Three Torsional States of CH3OD

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